Epithelium

Question 1

Epithelial tissue

Answer 1

Covers the body surface/ lines body cavities
Avascular
Derive nutrients via diffusion from blood vessels in the underlying CT

Question 2

What is the function of epithelial tissue cells in the intestine?

Answer 2

Absorption

Question 3

What is the function of epithelial tissue cells in glands?

Answer 3

Secretion

Question 4

What is the function of epithelial tissue cells in the skin?

Answer 4

Protection

Question 5

What is the function of epithelial tissue cells in the neuroepithelium?

Answer 5

Sensory

Question 6

What is the function of epithelial tissue cells in the myoepithelial?

Answer 6

Contractility

Question 7

Basement Membrane

Answer 7

Separates the epithelial tissue from CT
Basal lamina, collagen, glycoproteins and heparin sulphate form the BM
PAS-positive and seen with LM

Question 8

How can you classify epithelium?

Answer 8

Simple, stratified, and pseudostratified

Question 9

Simple Epithelium

Answer 9

All cells life on the basal lamina
3 types: squamous, cuboidal and columnar

Question 10

Stratified Epithelium

Answer 10

Has more than one layer and cell on the bottom layer lie on the basal lamina
4 types of stratified: squamous cuboidal, columnar and transitional

Question 11

Pseudostratified

Answer 11

All cells lie on the basal lamina but appear stratified because their nuclei are in different locations

Question 12

What can change the epithelium from one type to another?

Answer 12

A continuous abrasion or irritation.
Ex: stratified squamous non-keratinized to keratinized in the esophagus when milk diet is replaced by roughage in young animals
Or
Pathological change
Ex: pseudo-stratified columnar to stratified squamous in respiratory tract because of continuous smoke inhalation (metaplasia)

Question 13

What is the most prevalent epithelium?

Answer 13

stratified squamous (keratinized or nonkeratinized)

Question 14

How often is epithelia replaced?

Answer 14

Continuously replaced but the rate of replacement is variable

Question 15

Microvilli

Answer 15

1 micrometer high and 80 nm wide
Function: increase the surface area of absorptive cells (intestine and kidney) by 15-40 times
ABSORPTION

Question 16

Brush border

Answer 16

Microvilli grouped together, individual microvilli cannot be seen under the LM
AKA striated border

Question 17

Stereocilia

Answer 17

10- 20 um
Long immotile microvilli
Present in the epididymus
Function: absorb testicular fluid

Question 18

Cilia

Answer 18

Hair like processes 7-10um high, 0.2 um diameter
Consists of 2 central microtubules and 9 peripheral microtubule pairs
Function: moving cells and fluid past the cells

Question 19

What does each peripheral microtubule pair have?

Answer 19

2 little dynein arms and a motor protein that used energy from ATP to hook up the next pair of microtubules

Question 20

Kartagener Syndrome (Immotile Cilia Syndrome)

Answer 20

When a patient genetically lacks dynein arms
They’re infertile
More prone to respiratory syndrome

Question 21

Flagellum

Answer 21

Lagrer than cilium
Present in the sperm tail

Question 22

Intercellular Junctions

Answer 22

Provide adhesions between cells and restrict movement of materials in and out of the lamina

Question 23

Junctional Complex (terminal bar)

Answer 23

Membrane-associated structures that function in cell-to cell attachment of simple epithelia
3 components: Zonula occludens, Zonula adherens, and macula adherens

Question 24

Zoluna Occudens (ZO)

Answer 24

Surrounds the entire apical circumference of adjacent cells
Function: prevents substances from moving into the intercellular space from the lumen

Question 25

Zonula adherens (ZA)

Answer 25

Intermediate Junctions Surrounds the entire circumference of adjacent cells Variation: fascia adherens Function: binding of adjacent cells, linking cells to form a network

Question 26

Macula adherens (MA)

Answer 26

Desmosome Function: Provides firm binding between cells Well developed in the stratifed epithelia (skin)

Question 27

Hemidesmosome

Answer 27

Variation of a desmosome Binds the epithelium with the underlying CT

Question 28

Gap Junction

Answer 28

Couple adjacent cells metabolically and electrically Made of 6 connexins Communication between cells of signaling molecules (ions, hormones, AMP and GMP)- coordination

Question 29

Exocrine Glands

Answer 29

Secrete via a duct on the epithelium of its origin EX: salivary glands Modes of secretion: Holocrine, merocrine and aponcrine

Question 30

Endocrine glands

Answer 30

Not connected to epithilial surface, no duct and secrete into the bloodstream EX: paracrine and autocrine glands Location: thyroid glands

Question 31

where do paracrine and autocrine glands secrete?

Answer 31

Into the local extracellular space P: acts on nearby cells (not the ones that produce them) A: acts on the same cell that secretes it

Question 32

Mucus secretion

Answer 32

Viscous material that protects/ lubricates cell surfaces

Question 33

Serous Secretion

Answer 33

Watery secretion that is often rich in enzymes

Question 34

Mixed Secretion

Answer 34

Contains both mucus and serous

Question 35

Merocrine cells

Answer 35

Release only secretory granules by exocytosis with no loss of cytoplasm 99% of secretion

Question 36

Apocrine cells

Answer 36

Release secretory product with some apical cytoplasm Sweat glands in domestic animals

Question 37

Holocrine Cells

Answer 37

Release secretory product with all cytoplasmic contents (these cells die)

Question 38

What is the difference between Basil Lamina and the Basement Membrane?

Answer 38

BL is made of type 4 collagen and glycoproteins and is seen on the EM level BM is made of basal lamina and type 1 collagen fibers and can be seen on the LM level

Question 39

Simple gland

Answer 39

Duct does not brach

Question 40

Compound gland

Answer 40

Duct branches

Question 41

What controls the secretion of hormones by the endocrine glands?

Answer 41

Metabolic factors, secretion of other hormones and the nervous system

Question 42

Ciliogenesis

Answer 42

Centrioles duplicate, each centriole moves near the apical cell membrane (now called basal body) and gives rise one cilium.

Question 43

Simple Squamous

Answer 43

C: one layer, flat, spaced out L: blood vessels (endothelium), body cavities (mesothelium) F: Diffusion

Question 44

Simple Cuboidal

Answer 44

C: one layer, tightly connected, cubed/ rounded L: kidney, salivary glands, pancreas F: Absorption SC: microvilli

Question 45

Simple Columnar

Answer 45

L: small intestine, stomach, respiratory tract F: secretion and absorption C: Tall, central nuclei

Question 46

Simple Columnar Ciliated

Answer 46

L: uterus F: ovum transport, propels particles over epithelium surface C: Columnar, tall SC: cilia

Question 47

Pseudostratified Columnar (ciliated)

Answer 47

C: looks like more than one layer, nuclei at different places L: bronchus, epididymus F: cilia propels mucus and particles to the pharynx SC: cilia, goblet cells

Question 48

Stratified Squamous

Answer 48

C: multilayer, cuboidal based, polygonal middle, flat squamous superficial L: oral cavity, skin, pharynx, vagina F: Withstand abrasion and water proof SC: keratinized or non keratinized

Question 49

What has keratinized stratified epithelium?

Answer 49

skin

Question 50

Stratified Cuboidal

Answer 50

C: multilayer, cuboidal/rounded, L: exocrine gland ducts F:Provides robust lining

Question 51

Stratified Transitional

Answer 51

C: 4-5 layers thick L: bladder F: stretch and withstand urine toxicity

Question 52

Dynein Arms

Answer 52

Motor proteins that uses energy from ATP to hook up to the next pair of micro tubules